I'm not a fan of the whole living together thing, depending on what you're wanting for long term. However, I don't think it would decrease the likelihood of the two of you moving in together one day. It could actually speed things up for reasons of convenience. Living close by is totally different from moving in. You may spend a lot of time at one another's apartments and say "Well, hunny, since you're over here all the time anyway..." or "When are you going to start paying me rent."
There are just certain conveniences when you spend so much time with a person that can, but don't always, come with simply living close to one another.